The present invention relates to ignition coils, and, more particularly, to ignition coils having a high-voltage connection device or means for connecting an ignition cable to a secondary winding of the ignition coil.
An ignition coil is known, comprising a primary winding embedded in a cast resin portion, a secondary winding embedded in the cast resin portion and a high-voltage electrical connection device. The high-voltage electrical connection device includes at least one contact part electrically connecting a high-voltage end of the secondary coil to a conducting end portion of an ignition cable and a retaining part protruding beyond the cast resin portion and provided with a throughgoing aperture. A high-voltage connection of an ignition cable to an ignition coil is known from the DE-OS 35 06 929, in which the ignition cable end is introduced into an aperture of a connection tower and contacted by a pointed contact pin, with the contact pin being electrically connected via a contact wire to the end of a high-voltage winding. The connection tower, into which the ignition cable is inserted, is sealed against moisture by a shroud.
It is further common practice to use plug-type contacts for the connection of the high-voltage cable to the high-voltage winding. These plug-type contacts may be insulating plastic molded pieces. Such plastic molded pieces do not always guarantee a low-loss transmission, particularly with extremely high voltages, where moisture has penetrated, for example. In order to ensure safe handling of the high voltage, the plastic molded pieces would need to be of larger dimension. However, that would have the disadvantage that the connection area would have significantly larger dimensions and that the weight of the ignition unit would also increase.
The aim is to develop a high-voltage connection which removes this disadvantage and ensures, with the minimum weight possible, a low-loss transmission of the high voltage from the ignition coil to the ignition cable.